title: Depolarizing and calcium-mobilizing stimuli fail to enhance synthesis and release of endocannabinoids from rat brain cerebral cortex slices.
abstract: The concentrations of the endocannabinoids 2-arachidonoylglycerol (2-AG) and N-arachidonylethanolamine (anandamide) were examined in rat brain cerebral cortex slices and surrounding medium. Basal concentrations of endocannabinoids were similar to those identified previously in rat brain, with anandamide content being much lower (19 pmol/g) than that of 2-AG (7300 pmol/g). In contrast, basal concentrations in the surrounding medium were proportionally much lower for 2-arachidonoylglycerol (16 pmol/mL) compared to anandamide (0.6 pmol/mL). Incubation of slices with glutamate receptor agonists, depolarizing concentrations of KCl, or ionomycin failed to alter tissue concentrations of endocannabinoids, while endocannabinoids in the medium were unaltered by elevated KCl. Cyclohexyl carbamic acid 3'-carbamoyl-biphenyl-3-yl ester, an inhibitor of fatty acid amide hydrolase, significantly enhanced tissue concentrations of anandamide (and related N-acylethanolamines), without altering 2-AG, while evoking proportional elevations of anandamide in the medium. Removal of extracellular calcium ions failed to alter tissue concentrations of anandamide, but significantly reduced 2-AG in the tissue by 90% and levels in the medium to below the detection limit. Supplementation of the medium with 50 μM N-oleoylethanolamine only raised tissue concentrations of N-oleoylethanolamine in the presence of cyclohexyl carbamic acid 3'-carbamoyl-biphenyl-3-yl ester and failed to alter either tissue or medium anandamide or 2-AG concentrations. These results highlight the ongoing turnover of endocannabinoids, and the importance of calcium ions in maintaining 2-AG concentrations in this tissue.
authors.affiliation: School of Biomedical Sciences, University of Nottingham, Nottingham, UK.
authors.forename: Sarir
authors.initials: S
authors.lastname: Sarmad
authors.forename: Stephen P H
authors.initials: SP
authors.lastname: Alexander
authors.forename: David A
authors.initials: DA
authors.lastname: Barrett
authors.forename: Charles A
authors.initials: CA
authors.lastname: Marsden
authors.forename: David A
authors.initials: DA
authors.lastname: Kendall
mesh_terms: D000577:Amides; D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology; D063385:Cannabinoid Receptor Modulators / Q000096:biosynthesis* / Q000378:metabolism*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D063388:Endocannabinoids; D004983:Ethanolamines / Q000378:metabolism; D005989:Glycerides / Q000378:metabolism; D066298:In Vitro Techniques; D007294:Inositol / Q000378:metabolism; D008297:Male; D008994:Monoacylglycerol Lipases / Q000378:metabolism; D009829:Oleic Acids; D010169:Palmitic Acids / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000577:Amides; D000581:Amidohydrolases; D001095:Arachidonic Acids; D002118:Calcium; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D004983:Ethanolamines; D005989:Glycerides; D007294:Inositol; D008994:Monoacylglycerol Lipases; D009829:Oleic Acids; D010169:Palmitic Acids; D010743:Phospholipids; D053284:Polyunsaturated Alkamides; D011189:Potassium Chloride; D000099252:Fatty Acid Amide Hydrolases; C033595:N-oleoylethanolamine; C005958:palmidrol; C094503:glyceryl 2-arachidonate; C078814:anandamide